The turkey is roasting, the cranberry sauce is resting, and the pumpkin pie is good to go. It’s a scene being played out today in homes not just from California to New Jersey, but from Coventry to Neasden, too.Welcome to Britsgiving: the UK’s newest and completely unofficial holiday. Waitrose this week told the Guardian it estimates one in six Britons now celebrate Thanksgiving, a number that just seems to be going up and up. Sales of turkeys in November are up 95% on five years ago at Waitrose, and 135% year-on-year from Ocado. #Happythanksgiving is currently trending on Twitter across the UK.Thanksgiving is celebrated in the US on the fourth Thursday of each November. It is many people’s idea of a perfect holiday – a day off work and no presents, just a belt-breaking feast with family and friends followed by a doze in front of the TV. For a day which is so all-American, it might seem strange that Brits are jumping on the bandwagon – after all, the Pilgrims fled to the New World to escape persecution in England. In fact, it makes some sense – those early Pilgrim celebrations were based on the harvest traditions they’d known back home. That’s probably not why so many Brits are now tucking into pecan pie and eggnog, though.So why has Thanksgiving become such a big deal in the UK in the last five years? One reason is the sizeable expat community. Approximately 200,000 Americans now live in Britain, according to census data. Many Britons have American family or partners, or have been inspired to cook a Thanksgiving feast after a trip to the US. This is one reason Ocado launched a dedicated “American shop” online last year. Its Thanksgiving bestsellers are Libby’s Pumpkin Puree, Keebler Pie Crust and Borden Egg Nog.